


Bone Apple Teeth

by snasational



Series: Classic Vs The Multiverse [1]
Category: Undertale (Video Game)
Genre: M/M, Past Salphys, Scissoring, Sharing a Bed, Tribadism, Underswap Sans (Undertale)
Language: English
Status: Completed
Published: 2020-12-15
Updated: 2020-12-15
Packaged: 2021-03-11 00:15:16
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,035
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28096002
Author URL: https://archiveofourown.org/users/snasational/pseuds/snasational
Summary: His hands fly to Blue’s wrist. “Have you done this before?” He asks, realizing a bit too late that it’s basically an acceptance to Blue’s offer. The other nods enthusiastically.“Yes! Tons of times!”
Relationships: ClassicBerry, Sans/Sans (Undertale)
Series: Classic Vs The Multiverse [1]
Series URL: https://archiveofourown.org/series/2065212
Comments: 6
Kudos: 153





	Bone Apple Teeth

**Author's Note:**

> Yes I know, this is not Classic Cherryberry like i've promised twitter. I'll get there, I promise! But my fiance mentioned ClassicBerry tribbing once and, well, I ran with that idea!
> 
> This is not connected to my cherryberry oneshots. Not proofread or betad.

Sans thinks that Blue is hilarious. And cool. But maybe that has a lot to do with the fact that apparently he’s supposed to be some alternative version of himself with Papyrus’ personality. And anyone with his brother’s personality is automatically one of the bestest people in the entire world. No, he’s not exaggerating. Simply stating a truth. A scientific fact, really

Blue just sort of...fell on top of him one day. Literally. Sans is scrolling through his undernet feed while he’s supposed to be watching for humans and then his face is on the snow and there’s pressure on his spine. Blue is understandably spooked by the whole ordeal, and so is Sans. But if there’s one thing the Lab taught him, it's how to conceal emotions.

“Heh, falling for me hard aren’t you?” Sans said, face still in the ground. The cool thing about not having lips is that his voice is a projection from his soul, so Blue heard it loud and clear. 

“Wowzers! I’m so sorry friend, I didn’t mean to fall on top of you like that!” Blue had apologized frantically, scrambling to his feet and helping Sans stand back up. 

_ Wowzers  _ echoes in his skull reminding him of his brother. There was also the fact that Blue looks a whole lot like him. More cleaned up and brightly dressed, less tired and shabby looking. He also wears a cape, and holy shit if that isn’t the coolest thing. He should probably be more focused on Gaster’s theory on the multiverse being correct, but that’s a sack of worms he doesn’t want to touch. 

There’s snow stuck in the grooves of his bone. His shirt is now wet. His last pack of ketchup busted in his pants. The perfect set up for agitation, if Sans were capable of that nowadays. Instead he takes in Blue’s permanent grin, and the way his eye sockets seem to be grimaced in guilt. 

The blue eye lights amuse him. Skeleton eye lights aren’t naturally colored like that. It’s a trick with physical soul manipulation and is a lot harder to do than it looks. If Blue could do that, then he’s definitely got a strong hold on both the control of his magic and the science behind it. Respectable, if you asked him, Being able to do both is too difficult for him to want to try these days. Regardless, it really sets the whole ‘puppy dog’ vibe he gets from him.

Maybe that was his ulterior motive, to look nicer and softer than he really is. Classic Papyrus trick, one that hasn’t fooled him in years. “It’s no problem, buddy. I’m Sans.”

Blue’s not dumb by a long shot, so he understood with perfect clarity the situation they’re in. “Woah! That’s so cool, me too!”

The rest is history. Papyrus takes to his new house guest marvelously, and the two hit it off like they’ve been best friends since they were babybones. Papyrus doesn’t ask questions, Sans doesn’t provide answers. It’s just how their life works. Not the best way to handle things, he knows. 

Things get...complicated around the second week. Blue sleeps in his room, because Papyrus is weird about his sleeping space and can’t sleep unless he’s got the bed to himself. Blue is different in that aspect. He doesn’t mind sharing a mattress, nor does he mind impromptu middle of the night cuddling. Sans is the one doing the clinging, he naturally seeks out warmth in his sleep. 

Sans likes having Blue in his room. He cleans and makes the bed in the mornings. Body pillow and maid combo, Alphys would have a field day with this one. However, there’s an issue that makes him feel a whole lot like the teenager he hasn’t been in over a decade. Sans wakes up, huddled in Blue’s bubble, and feels shame. 

Magic is pulsating in his groin, a cunt being formed without his permission. He finds that Blue is already awake. His counterpart is staring at the dark blue glow in his pants, an amused tilt to his grin that makes him look even more like Sans. 

Why does that thought turn him on? Man, he really is a freak. 

Instead of acting all embarrassed by it, Sans plays it casual. “ _ Wet  _ a predicament I’m in.”

Blue snorts. Puns don’t bother him like they do Papyrus, so using them is a lot less fun. “Worry not, the Magnificent Sans is hardly bothered by indecency.” Blue winks, and then manipulates the magic in his right eye to take the shape of a star. Now that one is impressive, because you have to be artistically talented to pull off a shape like that. 

Sans laughs. “Oh man. You’re hilarious.” 

“I know.” He says, voice smug and cocky. Just like Papyrus. It makes Sans laugh harder. “Ahem, anyways, I can help you with that if you want!” 

Sans freezes. How is he supposed to respond to that? He hasn’t gotten it on since he broke up with Alphys, and doing the deed with an alternative version of himself seems...perverted. Is it incest if you’re the same person? Either way, Blue doesn’t seem to care. He rubs his sternum through his shirt, eliciting a nice gasp from Sans.

His hands fly to Blue’s wrist. “Have you done this before?” He asks, realizing a bit too late that it’s basically an acceptance to Blue’s offer. The other nods enthusiastically. 

“Yes! Tons of times!”

Sans tries not to let that get to his head. If Blue has had lots of sex, does that mean Papyrus has too? He shakes his metaphorical skull. Yeah. No. Not going there, he’d rather live in blissful ignorance than think of the corruption of his brother. 

“Oh.” Smart response, Sans. “Go ham then, I guess.” 

“Oh, I certainly will!” He sounds hungry. Like he hasn’t eaten in days, even though Sans witnessed him eat like five pounds of spaghetti last night. 

Blue is fast. He yanks Sans’ pants off quicker than Sans can think. The glow of his pussy lights up the room and makes Sans blush. It’s the most physical reaction anyone has managed to get out of him in years. Blue cooes at the sight of it and a finger begins to rub his slit. Instinctively, Sans spreads his legs for better access. 

“It’s exactly like mine!” His tone is appreciative. “So that automatically means it’s great!” 

“Kind of narcissistic, don’t you think?” He inhales sharply when that finger finally slips inside of him. 

“Not really.” He crooks his phalange at an angle he knows will drive Sans wild, because technically he’s fingering his own pussy. Does this count as masturbation? Weird masturbation with a clone, fun times. “Self love is perfectly acceptable, there’s nothing mentally ill about it.” 

There’s probably some screws loose in Blue’s head. It would be hypocritical of him to call Blue out on it, though. Another finger slips in. Sans closes his eyes. “Yeah. I guess you’re right.” 

They stay quiet, after that. The bedroom is full of small noises. Sans’ low panting, Blue’s pleased hums, the wet sound of something moving in and out of a pussy. Magic begins to twirl in his stomach, and when he crests it’s not explosive. Simply a satisfying burts of magic, the evidence of it coming in the form of his pussy spraying around Blue’s fingers. 

“Nice! You’re so pretty when you cum, you know.” 

Filthy, filthy words. Sans blushes even harder. He opens his eyes just as Blue is pulling his fingers out of his cunt. The other unhinges his jaw, a cerulean tongue snaking out and wrapping around the digits. Sans stares at this image, knowing damn well it’s going to be stuck in his head forever. 

“Wowzers! You taste pretty good, too!” 

“Bone apple teeth.” Sans says, braindead. 

His magic begins to disapitate, but before it can Blue’s finger is twirling around his clit. It’s over sensitive, but it keeps the magic interested enough to keep its form. Sans hisses and bucks his pelvis away. Message got, the pussy is staying. Blue takes the hint and backs off for a moment, allowing Sans to recuperate. 

“Can you make a body for me?” 

Sans blinks. That’s a weird request. Bodies are weird in itself, the feeling of skin unnatural and overwhelming. But...there’s a look in those eye lights, and the scientific side of Sans that he can’t shake no matter how hard he tries wants to poke and prod at it. Test all of it’s reactions, record all of the outcomes. 

He summons his body waist down, stopping at his kneecaps. Enough to where the skin doesn’t make him too sensitive to touch. Blue makes a pleased noise before shucking off his own pants. He’s already got his body formed, and along with it comes his soaking pussy. “Just lay there and let the Magnificent Sans do all the work.” He purrs. 

Sans is okay with that. Doing nothing is what he’s best at, after all. 

He lets Blue manhandle him into place. On his side, Blue straddling a thigh and his ankle thrown over a bony shoulder. He’s seen this before, in that lesbian porn he’d watch with Alphys. She called it scissoring, but they broke off before Sans got to try it with her. It was a memory he almost completely forgot about.

Blue scoots forward until their lips touch. That would have been totally romantic if Sans wasn’t talking about pussy lips, he thinks. His counterpart sighs contently at the contact, shifting his hips so they rub together gently. He’s testing the waters, trying to gauge out Sans’ reaction to the new stimulation. 

Maybe there’s a scientific part of Blue, too. He may have Papyrus’ personality and ambitions, but deep down he’s still a version of Sans. Things are always going to be unnecessarily complicated in that head of his. Sans takes comfort in the knowledge and encouragingly rolls his hips into Blue’s cunt. 

Blue’s grip tightens, and suddenly he’s hugging Sans’ leg to his chest and grinding down  _ hard.  _ Sans moans, not expecting things to be cranked up so fast. But he’s come to learn that Blue doesn’t do anything slow, so by now it shouldn’t come to a surprise. He bears down and humps into him quick and hard, each drag more pleasurable than the last. 

They’re a perfect match. Their clits rub together, their folds dance with each other, and both are equally as wet as the other. It makes the slide fantastic. This is awesome, almost as fun as being penetrated or eaten out. Though it’s been years since Sans got to experience that. His breathing quickens, and he twists his fingers into the bed sheets and arches his spine. 

“Oh, Sansy, that feels so good.” Blue groans. “You’re the best! So good for me.” 

Sans’ eye lights blacken out entirely at the force of his second orgasm. It’s intense, taking his soul by surprise and turning him into putty. He never wants this euphoria to stop, because nothing will ever compare to this feeling of complete and utter satisfactions. He hears Blue cry out, feels the twitching of his hips and the way his pussy pulses against his own. Wetness floods down his thighs and ruins their sheets. 

They stay in that position for a few moments longer, until Blue is dropping his leg and falling back onto the mattress. It bounces slights with the force of his fall. “Wowzers.” He begins after he’s caught his breath. “We should do that again!”

Sans props himself up on his elbows and gives him a look. “Insatiable.” 

Papyrus could come home at any moment. He can’t miss any more days of work. He wants to sleep because he’s bone tired. But seeing Blue look so fucked out, his face flushed light blue and his eyelights white because he doesn’t have the energy to maintain his persona...it makes Sans question his stance on calling it quits for the day.

“Please?” He begs, the puppy dog effect still working even without those comical eyes. 

Sans is a weak man. “Fine. One more round.”

They go for three more. 

**Author's Note:**

> Twitter is @ askeletonthot
> 
> Comments and Kudos are always appreciated!


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